By Dan Weil Ark also unloaded one of the top social media platforms. In addition, it bought biotechnology stocks. Investment heavyweight Cathie Wood, chief executive of Ark Investment Management, sold shares of a major electric vehicle maker for the third consecutive day Thursday. Ark also unloaded one of the top social media platforms. In addition, it bought biotechnology stocks, a financial exchange stock and a robotics stock. (All valuations listed below are as of Thursday’s close). Ark funds sold 37,551 shares of Tesla (TSLA) – Get Tesla Inc Report, valued at $40.5 million. Wood has said i…